394 



the whole aerial axis died back to a short stump. New, weak shoots then 

 began to sprout. We have cited this example, in order to show that the 

 effect of over-fertilization, although it takes place through the soil, does not 

 make itself felt at first at the base of the axes but on the peripheral organs, 

 the leaves. 



In comparative experiments with Fuchsia cuttings ^ a continued fer- 

 tilization with small amounts of ammonium sulfate resulted in a noticeable 

 increase in growth and an enlargement of the leaves. The epidermal cells 

 of the leaves had thinner walls and the wood ring of the branches made a 

 weaker development. The starch content was smaller, the chlorophyll con- 

 tent larger, the period of growth lengthened. When the fuchsias were 

 protected from autumnal frosts, by being brought into a greenhouse, they 

 had time to ripen normally, and the differences as compared with unfer- 

 tilized plants disappeared. The fertilized ones had rather the advantage 

 in a greater growth. Here we have a result such as is evident in growing 

 fodder beets. The addition of large amounts of nitrogen retards the ripen- 

 ing process. If the plants can reach maturity before frost, so that the leaves 

 ripen normally, we obtain the desired results from fertilization, i. e., the 

 production of greater amounts of material, with a normal supply of reserve 

 substances. But, as a rule, the climatic conditions prevent the termination 

 of growth and winter finds the organs in an immature condition. 



The disadvantage of harvesting insufficiently matured plants has been 

 emphasized under "agricultural crops," Such plants have a greater tendency 

 to decay. 



The same results were obtained with comparative fertilization experi- 

 ments with Erica. The red blossoming varieties developed less vividly red 

 or almost bluish red blossoms in the series of experiments with a one-sided 

 nitrogen fertilization ; their habit of growth was more drooping and the 

 blossoms set less abundantly. The fertilized specimens suffered so greatly 

 from Botrytis cinerea in winter that most of them died, while unfertilized 

 plants of the same varieties from the same place came through the winter 

 uninjured. Bluth- carried out an experiment which showed the eft'ect of 

 a highly concentrated solution of all the nutrient substances. The Ericas, 

 in the second year of cultivation, were given continued supplies of a one- 

 tenth per cent, solution of Wagner's nutrient salt. After ten to twelve days the 

 leaves became a darker color and their growth stronger, but the plants 

 showed a greater sensitiveness to the action of the sun and drought, in com- 

 parison with many hundreds of unfertihzed specimens of the same variety. 

 The new lateral shoots of certain tender varieties (£. hiemalis, E. congesta, 

 etc.) developed a drooping and often curved habit of growth. Hard 

 needled varieties {E. hlanda, E. niediterranea, E. verticillata, E. mammosa) 

 retained their erect habit of growth but the buds set in a strikingly small 



1 Sorauer, P., Einfluss einseitiger Stickstoffdiingung-. Zeitschr. f. Pflanzen- 

 krankheiten 1897, p. 287. 



2 Zeitschr. f, Pflanzenkrankh. 1895, p. 186. 



